Not having much luck with these roses!!

Last time black spot this time looks like rust or magnesium problem going by my book but thought I'd let you guys advise as my roses that had the black spot seem to be doing ok

What do you think, it's not all of the rose just half. (South facing)

 

Maybe a better picture

 

have you a tom cat or fox as it looks like it has been sprayed , my mum has a small conifer at the start of her path and she caught the fox spraying its made one side turn brown as well

 

Yeah we do have a cat that likes to visit as there is a birds nest in the conifer next to this rose, I will have to look out for it next time

 

I'm thinking along the same lines as Spruce, not rust but some form of chemical damage, either natural or manufactured.

 

I'm in Northumberland about 3 miles from the coast, I have removed the effected canes but it seems to be spreading :(
Wouldn't care the flowers it has produced are stunning!